Purpose: To assess the possibility of reducing radiotherapy doses without compromising efficacy in the management of patients with stage I seminoma.
Patients and methods: Patients were randomly assigned 20 Gy/10 fractions over 2 weeks or 30 Gy/15 fractions during 3 weeks after orchidectomy. They completed a symptom diary card during treatment and quality-of-life forms pre- and post-treatment. The trial was powered to exclude absolute differences in 2-year relapse rates of 3% to 4% (alpha = .05 [one sided]; 90% power).
Results: From 1995 to 1998, 625 patients were randomly assigned to treatment. Four weeks after starting radiotherapy, significantly more patients receiving 30 Gy reported moderate or severe lethargy (20% v 5%) and an inability to carry out their normal work (46% v 28%). However, by 12 weeks, levels in both groups were similar. With a median follow-up of 61 months, 10 and 11 relapses, respectively, have been reported in the 30- and 20-Gy groups (hazard ratio, 1.11; 90% CI, 0.54 to 2.28). The absolute difference in 2-year relapse rates is 0.7%; the lower 90% confidence limit is 2.9%. Only one patient has died from seminoma (allocated to the 20-Gy treatment group).
Conclusion: Treatment with 20 Gy in 10 fractions is unlikely to produce relapse rates more than 3% higher than for standard 30 Gy radiation therapy, and data on an additional 469 patients randomly assigned in a subsequent trial support and strengthen these results. Reductions in morbidity enable patients to return to work more rapidly. Prolonged follow-up is required before any inference can be made about any impact of allocated treatment on new primary cancer diagnoses.